A simple random sample (SRS) of 100 of a certain popular car in 1997 found that 20 had a certain minor defect in the brakes. An SRS of 400 of the same car in 1998 found that 50 had the minor defect in the brakes. Let and be the proportion of all cars of this model in 1997 and 1998, respectively, that actually contained the defect. A 90% confidence interval for is:.A. 0.075±0.085.B. 0.075±0.071.C. 0.075±0.043.